Dimethylpolysiloxane, a typical example of organopolysiloxanes, is known as silicone oil and used as fiber treatment agent, resin modifier, water repellent, cosmetic material, mold release, paint additive, etc. in various industrial fields.
Also, dimethylpolysiloxane in which organic functional groups such as amino, epoxy, hydroxyl, carboxyl, polyoxyalkyl, etc. are introduced at the end of its molecule or side chains thereof, are widely used for various purposes as modified organic silicone.
If dimethylpolysiloxane is provided with antibacterial activity in addition to its inherent lubricating, glossing, surface protection and water repellent effects, the compound will be more useful in various applications. That is, it is considered to introduce substituents having antibacterial activity to dimethylpolysiloxane. However, environments, in which antibacterial activity is required, are varied and requirements for antibacterial spectrum are also varied. Further, low toxicity is prerequisite when the compound is used in an environment, in which it may be in contact with human bodies.
Many and various antibacterial compounds including quaternary ammonium compounds are known. Guanidyl compounds, some of which are known to have biological activity such as antimalarial, are examples of such compounds.
For instance, bisbiguanides, which have biguanidyl groups on both ends of an alkylene chain, have strong germicidal and antibacterial activity and some of them have been widely used as germicides and disinfectants and are studied for a long time.
However, the mechanism of germicidal activity of these compounds is not yet quite clearly understood and presence of the biguanidyl group does not always cause germicidal activity. It is well known that biological activity of biguanide compounds remarkably varies depending on the species of substituents. (Refer to: J. Chem Soc., 729 (1946).) Also it is reported that germicidal activity and antibacterial spectrum of the above-mentioned bisbiguanide compounds are largely influenced by length of the alkylene chain, species of end substituents, etc. (Refer to: Brit. J. Pharmcol. 9, 192 (1954), for instance.)
The object of the present invention is to provide a class of low toxicity antibacterial polysiloxane compounds, which can be applied to the surface of various materials or incorporated in resins and provide them with antibacterial activity.
We prepared a class of novel compounds, which comprise a guanide compound to the molecular end of which high molecular polysiloxane was attached and found that some of them have strong germicidal activity and are practically useful as antibacterial agents. These compounds have at least a guanidyl group, which is of low toxicity to the human body, as an active moiety and thus can be used in a wide range of application field. In these compounds, the germicidal moiety is chemically bonded to high molecular polysiloxane and, therefore, the germicidal activity is maintained for a long time and deleterious effect to the environment and the human body is reduced in comparison with the conventional physical incorporation of a germicidal substance in polymer materials.